Wireless telecommunication systems facilitate radio communications between a wireless station, e.g., a cellular telephone (analog, digital and PCS), and other communication devices. Typical of wireless telecommunication systems is a cellular telephone system that facilitates calls to and from cellular telephones within a predetermined service area. The service area of a cellular telephone system is normally subdivided into areas known as “cells.” Associated with each cell is a base station antenna that facilitates radio communications with cellular telephones within the cell. The base station antennas of all the cells in a service area are in communication with a mobile switching center (“MSC”) that establishes a communication channel between the cellular telephone located in the service area and another telecommunication device. In operation, the MSC establishes a communication channel between a cellular telephone located in the service area and another telecommunication device (e.g., another person's cellular telephone or a land-line telephone). Once the channel is established, communications are relayed between the cellular telephone, the base station, the MSC and the other telecommunication device.
An important characteristic of many wireless stations is mobility. In the case of cellular telephones, a subscriber to a cellular telephone system can conduct calls in the service area and, in many cases, in areas outside of the subscriber's service area. This mobility has lead to the development or proposed development of tools for determining the location of a wireless station. For instance, when a cellular telephone is used to place a “911” emergency call, determining the location of the cellular telephone would be highly desirable so that emergency personnel can assess how best to reach the individual in distress. This is especially important in situations involving remote locations where precise locational information cannot be given or the individual cannot provide locational information due to an injury.
A number of devices have been developed for providing locational information of wireless stations. For example, in cellular telephone systems, the communication protocol used within the system identifies the cell in which a cellular telephone is located when the call connection is established. In many applications, this may provide sufficient locational information. However, because the area covered by a cell can be large, especially in rural settings, more accurate devices have also been developed. For instance, various devices have been developed that use information provided by two or more antennas to provide locational information by triangulation.